Introduction: the article provides a theoretical overview of the “city-region” concept. The analysis of research papers devoted to this concept demonstrates the growing interest to the city studies in the context of economic globalization, spatial and organizational transformations within the countries. Objectives: to reveal the city-region study potential by considering it through the approaches of modern geographical science and the methodology of international relations. Methods: historical-chronological and comparative-descriptive. Results: based on the theory of new regionalism, authors show that regionalization, along with states and regions, is inherent in large cities with adjacent territories (conurbations) as well. The authors highlight some markers, which specify “city-region” concept, and distinguish it from other close concepts such as “world city” and “global city”. An overview of the main interpretations of the city-region is given, resulting in a conclusion about the need for an interdisciplinary approach to its study. Conclusions: a city-region is a city with a population of more than one million people, an agglomeration model of growth and a certain type of zoning. It is capable of becoming a global city in the future, but at the current stage, it does not have all the necessary characteristics. The inclusion of cities-regions into the research field of international relations will increase the range of subnational actors, as well as provide an opportunity to obtain new results in the study of city-regions and strengthen interdisciplinary research of modern cities.